魁！小野の塾　PHPで簡単なプログラムを作ってみようの巻　第８話

<?php
	// db resource
	$db	= new mysqli('localhost', 'root', '', 'pjin');
	$db->set_charset("utf8");

	// $_POST -> $request
	$request	= [
		'author'	=> $_POST['author'] ?? '',
		'content'	=> $_POST['content'] ?? '',
		'action'	=> $_POST['action'] ?? ''
	];

	// create
	$errors	= [];
	switch($request['action']){
	case 'create':
		// error check
		if(empty($request['author'])){
			$errors['author'][]	= '名前を入力して下さい。';
		}
		if(mb_strlen($request['author']) > 128){
			$errors['author'][]	= '名前は128文字以内で入力して下さい。';
		}
		if(empty($request['content'])){
			$errors['content'][]	= '内容を入力して下さい。';
		}
		if(mb_strlen($request['content']) > 65535){
			$errors['content'][]	= '名前は65,535文字以内で入力して下さい。';
		}

		if(count($errors) > 0){
			// エラーがあれば終了
			break;
		}

		// 登録処理
		$sql	= "insert into board(author, content) values (?, ?)";
		if($stmt = $db->prepare($sql)){
			$stmt->bind_param("ss", $request['author'], $request['content']);
			$stmt->execute();
			$stmt->close();
			// 登録後に空にします。
			$request	= [
				'author'	=> '',
				'content'	=> ''
			];
		}
		break;
	}

	// 検索処理
	$rs	= [];
	$sql	= "select * from board order by id desc";
	if($stmt = $db->prepare($sql)){
		$stmt->execute();
		$stmt->bind_result($id, $createdAt, $author, $content);
		while($stmt->fetch()){
			$rs[]	= [
				'id'		=> $id,
				'createdAt'	=> $createdAt,
				'author'	=> $author,
				'content'	=> $content
			];
		}
		$stmt->close();
	}

	// db resource close
	$db->close();
?>

	<main class="container">

<?php if(count($errors) > 0){ ?>
		<div class="alert alert-danger" role="alert">
			<h4 class="alert-heading"><i class="fas fa-exclamation-triangle"></i> エラー</h4>
			<ul>
	<?php foreach($errors as $err){ ?>
		<?php foreach($err as $e){ ?>
				<li><?php echo htmlentities($e) ?></li>
		<?php } ?>
	<?php } ?>
			</ul>
		</div>
<?php } ?>

		<form action="<?php echo $_SERVER['SCRIPT_NAME'] ?>" method="POST">
			<input type="hidden" name="action" value="create">
			<div class="form-group row">
				<label for="author" class="col-sm-2 col-form-label">名前</label>
				<div class="col-sm-10">
					<input type="text" name="author" id="author"
						value="<?php echo $request['author'] ?>"
						class="form-control<?php if(isset($errors['author'])){ echo ' is-invalid';} ?>"
						placeholder="名前" autofocus>
				</div>
			</div>
			<div class="form-group row">
				<label for="content" class="col-sm-2 col-form-label">内容</label>
				<div class="col-sm-10">
					<textarea name="content" id="content"
						class="form-control<?php if(isset($errors['content'])){ echo ' is-invalid';} ?>"
						rows="10" placeholder="内容を入力してください"><?php echo $request['content'] ?></textarea>
				</div>
			</div>
			<div class="form-group row">
				<div class="offset-sm-2 col-sm-10">
					<button type="submit" class="btn btn-primary"><i class="fas fa-paper-plane"></i> 送信</button>
				</div>
			</div>
		</form>